Did city commissioners provide a specific list of how they would spend the 0.3 percent sales tax that they've proposed for infrastructure?

Yes. Commissioners approved a binding resolution that spells out what type of projects the sales tax money could be spent for.
Here's the relevant wording: "for the purposes of improving and maintaining public streets and sidewalks, constructing and maintaining improvements to the stormwater pump station and related stormwater facilities in the city north of the Kansas River, constructing and maintaining recreational trails and paths, purchasing fire apparatus and related fire equipment, and such other related street, storm water and recreational path infrastructure, and fire equipment purposes as may be in the best interest of the city."